1. Field of the Invention
The present invention generally relates to dust collecting devices of the type using bag-like cloth or fabric filtering elements and, more particularly, to a means for cleaning the filtering elements in such devices to discharge accumulated particulates.
2. State of the Art
It is well-known to accomplish large-scale cleaning of suspended particles from gaseous streams by passing the streams through a device having a housing wherein are suspended a plurality of flexible cloth or fabric filtering elements that are formed as cylindrical bags. Such devices are commonly known as bag houses. After a period of operation, the particles that accumulate on the filtering elements must be removed. That is typically done by shaking or vibrating the elements to dislodge the particles, which then fall into hoppers or other recepticles disposed at the bottom of the housing.
A problem with bag-type filters is to effectively clean the elements without undue wear. Typical practice today is to impart a gentle shaking or oscillatory motion to the bag-support structure and, at the same time, to direct a reverse current of air through the elements to loosen the dust accumulations. In applications such as filtering the fumes discharged by cupolas in steel foundries, a gentle shaking action is not sufficient to dislodge the dust that agglomerates on the filtering elements, and more vigorous shaking has been found to be deleterious to the filtering elements, especially those formed of synthetic fabrics such as fiber glass. The vigorous back-and-forth bending eventually snaps the synthetic strands. Workers in the art, however, have found that bags made of synthetic fibers have superior filtering characteristics when used in high-temperature or moist atmospheres or when cleaning certain acidic gases and, accordingly, have sought effective means for cleaning such filtering bags.